December 29, 1904] 



NA TURE 



195 



added largely to previous records in species new to 

 science, in others new to British lists, and in the fuller 

 knowledge of the life-histories of species already 

 known. The task was no easy one, but none more 

 competent could have undertaken it, and it has been 

 accomplished in a wa)' to deserve the f,'ratitude of all 

 interested in the freshwater AlgEe of Great Britain and 

 Ireland. 



The " Treatise " is one of the well known and excel- 

 lent Cambridge Biological Series. Its aim is stated as 

 " to give the student a concise account of the struc- 

 ture, habits and life-histories of Freshwater Algae, and 

 also to enable him to place within the prescribed limits 

 of a genus any ."Mga he may find in the freshwaters of 

 the British Islands." To do this within the limits of 

 an octavo volume of less than 400 pages, in which 

 are numerous illustrations, is a task possible of 

 accomplishment only by one very familiar with the 

 subject and skilled in concise expression ; but that it 

 has been successfully done will, we think, be the verdict 

 after testing the book thoroughly. The views and 

 labours of others receive due attention, and footnotes 

 direct the student to the original publications; but 

 Prof. West is no mere follower of the views of others, 

 and much of the excellence of his book is due to his 

 personal researches and to the conclusions he has 

 drawn from them. In the preface we read that " there 

 is no single book, or accessible set of books, by means 

 of which a student can hope to accurately identify one- 

 third of the freshwater .Algae he may find in a single 

 day's ramble through a reasonably productive part of 

 the country." With the aid of this guide he may 

 hope to determine the genus of all save the more 

 critical forms, and even the species in some of the 

 genera. But the book is much more than a guide to 

 the identification of genera and species. The intro- 

 duction gives a very readable and interesting general 

 account of freshwater Algs in respect of their habitats, 

 distribution, relations to and associations with certain 

 other plants, and even with the lower animals, some 

 of these correlations being of verj' curious kinds. 

 Their relations to temperature (some thriving on ice 

 and snow, while others can live around hot springs 

 at 94°-5 C), to surface conditions and exposure, and 

 to geological strata are discussed; and the author's 

 wide experience in field work gives much interest to 

 the discussion. Mountainous districts are the richer, 

 especially in Myxophyceae and Conjugatae, of which 

 latter the desniids and Mougeotia are peculiarly 

 numerous in species in these regions. The older 

 Pateozoic and Igneous regions are preeminent in this 

 respect, and the richest localities in Britain, " and 

 perhaps in the whole of Europe," are tarns and peat- 

 bogs in hollows of the Lewisian gneiss of north-west 

 .Scotland, while the fen district of eastern England is 

 the poorest in Britain in freshwater species of -Alga. 



The methods of collection, of cultivation (so im- 

 portant as a means of study), and of preservation for 

 luture use are described. The structure, cell-contents, 

 nutrition and growth of the cells and plant-bodies, the 

 methods of multiplication by division and of reproduc- 

 tion (asexual and sexual), the alternation of gener- 

 ations, the range of polymorphism observed in some 

 species, and alleged to occur in others, are considered, 

 NO. 1835, VOL. 71] 



and the belief is stated that the higher types have 

 originated by gradual evolution from the more lowly 

 types, but that the latter still persist, and must not 

 be confounded with stages in the life-histories of the 

 higher forms, as the author believes has been done 

 by some. The phylogeny and scheme of classification 

 take full note of the discoveries and views of Black- 

 man, Bohlin, Borzi, Chodat, Wille and others, com- 

 bined with the author's own discoveries. 



.Six great classes are recognised, of which four 

 (Rhodophyceae, Phaeophyceae, Bacillariacea or dia- 

 toms, and My.xophyceae) are of the usual compass, the 

 two former including few species in fresh waters. The 

 Heterokontae, a group proposed a few years ago by 

 Luther for a few families characterised by yellowish- 

 green chroniatophores and the production of oil as a 

 reserve of food, are separated off from the other green 

 Algae ; but all the remaining green types are included 

 in the class ChlorophyceK, the methods of reproduction 

 not being accepted as justifying their separation into 

 different classes. Chlamydomonas is regarded as 

 nearest to the origin from which all have sprung, 

 scarcely different from the Flagellata, and the divergent 

 lines of increasing complexity are traced, three chief 

 tendencies, as pointed out by Blacknian, showing 

 themselves, and resulting in three types of structure, 

 viz. the motile coenobium, the multinucleate unicellular 

 coenocyte, and the multicellular aggregate, the cells of 

 which become more and more intimately related and 

 specialised to form the definite organism. This last 

 type has resulted in the most complex structures among 

 Algae, and is regarded as having given origin through 

 them to the archegoniate plants. 



All grades of classification of the British freshwater 

 Algae down to genera are defined in this " Treatise," 

 and each genus is well illustrated by drawings from 

 the plants themselves, with few exceptions original. 

 The number of British species is stated under each 

 genus, and information is often added regarding the 

 more representative species. For each genus also the 

 synonymy is given, along with references to the litera- 

 ture. 



Prof. West's treatment of his subject is instructive 

 and stimulating, and the book will do much to extend 

 the study of these plants. But it also excites the hope 

 that he vi-ill supplement this work by giving us one 

 descriptive of all the species and varieties of these 

 .Mgje that have been found in Britain, with, if practic- 

 able, indications of those likely to be added to the 

 flora. He has pointed out the need of such a guide, 

 and has proved that it could be attempted by none 

 more fit to make it a success. 



The volume on " British DesmidiaceEe " also illus- 

 trates the extraordinary advance in the study of British 

 freshwater .Alga in recent years, due to the researches 

 of but a few workers, among whom the authors are 

 in the front rank. In this monograph will be brought 

 together not only much information that, though pub- 

 lished, was often scarcely accessible, but also much 

 acquired through researches in many regions, from 

 Shetland to Cornwall, in Wales and Ireland, and not 

 yet published. Nearly 700 species and 450 varieties are 

 now known from the British Islands (being rather 

 more than one-third of all named species). Of these 



